The purpose of this research was to identify the impact of Contextual Teaching and Learning (CTL) on the ability of understand of mathematical concepts. This study used a qualitative descriptive approach to the type of study is a library research, the data obtained from various sources related to the matters under investigation in the form of books and literature or the results of research and writings related to research the journal is both national and international journals. The results of this study indicate that Contextual Teaching and Learning (CTL) can have an impact on students' understanding of the concept. In order to achieve this, teacher should know and master various ways to teach students with Contextual Teaching and Learning (CTL) that can be used to improve students' ability to understand concepts in mathematics learning. The implication in this research is a collection of results of other people's research or theories underlying the problem that is wanted to be studied.

This study aims to determine the effect of the Contextual Teaching and Learning (CTL) learning model on the ability to understand the concepts of class VII students of SMP 16 Kota Bengkulu. The research carried out was quasi-experimental with a population of all students in class VII of SMP 16 Kota Bengkulu totaling 218 students. Samples were taken by random sampling technique and a sample of 60 students was obtained, 30 students in the VIIA class as the experimental class, 30 students in the VIIE class as the control class. Data collection using Instrument concept understanding ability test. Data analysis techniques using Ancova. The results showed that there was the influence of the Contextual Teaching and Learning (CTL) learning model on the conceptual comprehension ability of seventh grade students in Bengkulu City 16 Junior High School at 80.50% with an average of 82.75 and there was an effect of an initial ability of 60.50% with an average average of 82.80. It can be concluded that the ability to understand students' concepts is better by using the Contextual Teaching and Learning (CTL) learning model.